Abstract
A method of sulfurization of fluorine-containing carbon materials obtained by heating of carbon materials in contact with fluorocarbons or fluorine-containing derivatives thereof. Claimed method allows obtaining a wide range of fluorine-containing carbon materials with grafted sulfur functionalities. Claimed materials can be used in industry as novel acid-base catalysts with high stability in any aggressive medium. Another embodiment of the invention can be used for producing electrodes of metal-sulfide batteries or as a specific sorbent, metals or nanoparticles support.
Claims
1. The method for preparing a functionalized carbon material with CF.sub.2SO.sub.3H groups covalently bonded with the carbon matrix directly, or through a (per)fluoroalkylene chain, by chemical modification of a carbon material that contains fluoroorganic groups covalently bonded with the carbon matrix and capable of alkylating sulfur atoms with the formation of CF.sub.2S bonds [Material (FC)], said method comprising: contacting of said Material (FC) with a sulfur-containing compound that contain an atom of sulfur capable of alkylation [Reagent (S)], and heating of said Material (FC) while in contact with said Reagent (S) at a temperature sufficient to initiate the chemical reaction between said Material (FC) with said Reagent (S), wherein said atom of sulfur of the Reagent (S) is alkylated by said fluoroorganic groups of said Material (FC), and hydrolytic treatment of the obtained product of alkylation, and oxidation of the product of the hydrolytic treatment.
2. The method according to claim 1, wherein the Material (FC) is selected from the group consisting of the fluorinated activated carbon, fluorinated coke, fluorinated pitch coke, fluorinated charcoal, fluorinated carbon fibers, fluorinated carbon nanotubes, fluorinated carbon black, fluorinated graphene, fluorinated carbonizates, fluorinated nanodiamonds, fluorinated fullerenes or fluorinated fullerite.
3. The method according to claim 1, wherein the Reagent (S) is a substance selected from the group consisting of hydrogen sulfide, mercaptans, the salts of hydrogen sulphide, the salts of mercaptans, organic disulfide, sulfur oxide, sulfurous acid salts, thiourea, carbon disulfide, chlorosulfonic acid, polysulfide ion, and elemental sulfur.
4. The method according to claim 1, wherein said Material (FC) is obtained by chemical modification of a carbon material with the organofluorine compound, selected from the group consisting of fluorocarbons, halofluorocarbons, hydrofluorocarbons, or fluorinated alcohols.
5. The method according to claim 1, wherein the Material (FC) contains oxygen and/or hydrogen.
6. The method according to claim 1, wherein the Material (FC) contains double carbon-carbon bonds in the carbon matrix, capable of alkylating the sulfur atom of Reagent (S).
7. The method according to claim 1, wherein the interaction of Material (FC) with Reagent (S) is carried out in the liquid phase.
8. The method according to claim 1, wherein the interaction of Material (FC) with Reagent (S) is carried out in the gas phase.
9. The method according to claim 1, wherein the oxidation of the product of the hydrolytic treatment is carried out with a substance selected from the group consisting of hydrogen peroxide, nitric acid, nitrous acid, oxygen-halogen compounds, or molecular oxygen.
Description
[0024] The invention is illustrated by the following Examples: [0025] 1. 3 g of fluorinated carbon material (fluorine content is of 1.72 mmol/g, chlorine is of 2.02 mmol/g), which was obtained by reacting when heated to 560 C. of Freon R-12 (Difluorodichloromethane, CF.sub.2Cl.sub.2) with SCN active carbon (raw materialvinylpyridine resin) was introduced in a contact with 3 g of trihydrate of sodium hydrosulfide (NaHS.Math.3H.sub.2O, pur.) in a Teflon beaker in a hermetic glass autoclave at 145 C. for 12 hours. After the reaction product was washed with water, 5% hydrochloric acid, again with water and treated with 50 ml of 1.00 g of Berthollet salt in 2M nitric acid for 18 hours. The resulting product is separated from the solution, washed with water, poured into 12 hours in 3% sodium carbonate solution to neutralize acids and remove adsorbed sulfates, thoroughly rinsed with water and treated with 5% hydrochloric acid to restore acid state of sulfonic groups. After treatment with acid, material was washed with water to pH 4.5. The resulting carbon material according to the results of chemical analysis contains 1.65 mmol/g of fluorine, 0.62 mmol/g of chlorine and 0.45 mmol/g of sulfur. Unlike the original fluorinated material having a XPS spectrum clear but slightly asymmetric signal of fluorine (at 686.6 eV) and chlorine (doublet 199.5 eV, 201.0 eV) derivative after the stage of hydrolysis has about a half strength signal of chlorine (at 199.7, 201.4 eV) at nearly constant strength of fluorine more asymmetric signal (in 686.7 eV), and complex signal of sulfur in mercapto-form (with 162.8 eV and 164.0 eV complex components) (FIG. 4). By TPD-mass (FIG. 5) method it was shown that final product desorb sulfur in SO.sub.2 form (m/z 64 and 48) in a temperature range of 125-475 C. with maximums at 220 and 350 C. Signal with m/z 32 is negligible in all investigated temperature range, that confirm absence of elemental sulfur in sample. In the temperature range of sulfonic groups decomposition also observed evolving of CO.sub.2 and H.sub.2O (m/z 44 and 18 respectively). Intensive CO evolution (m/z 28) observed above 320 C. with maximum at 730 C. and can be assigned to carbonyl or ether groups [17]. Water forms, desorbed at the temperature exceeded 120 C. can be assigned to hydrate forms of HSO.sub.3-functionalities. Evolution of HF (m/z=18) is observed at a temperature higher than 520 C. and occurs in a small quantity. Catalytic study in the gas phase reaction of i-propanol dehydration give a temperature of 100% conversion is 115 C. for this sample (250 mg), showing an excellent stability in reaction media in cyclic regime. By coulometric titration (FIG. 6) it was shown the presence of strong acid function on a surface of a sample (0.45 mmol/g). According to the final sample properties established by methods of TPD-IR, mass spectrometry, catalytic tests and coulometric titration it's can be concluded that sulfur contained in the sample as a grafted sulphonic acid state. [0026] 2. Synthesis was conducted similar to that described in Example 1, but as a starting carbon material was taken Norit 830W active carbon, which was processed with perfluoroethylene bromide (BrCF.sub.2CF.sub.2Br, Fluobrene) at the temperature of 500 C. This material contains 1.84 mmol/g of bromine and 1.32 mmol/g fluorine and have a S.sub.BET=905 m.sup.2/g. Instead of sodium hydrosulfide was used sodium mercaptoacetate concentrated solution (HSCH.sub.2COONa), synthesis was performed at 120 C. during 12 h, and hydrochloric acid hydrolysis stage was performed by autoclaving S-adduct at 120 C. for 2 hours to hydrolyze grafted mercaptoacetic acid to acidum lacticum and surface thiol. After hydrolysis, product was oxidized by treatment of 3 g NaNO.sub.2 in 3M nitric acid solution during 6 h. Based on the results of chemical analysis the resulting product contains 0.93 mmol/g of sulfur, 1.20 mmol/g of fluorine and not containing significant amounts of bromine. Resulting product have a S.sub.BET=855 m.sup.2/g The results of TPD-mass, SO.sub.2 desorption and catalytic studies show properties close to the product of Example 1. [0027] 3. 3 g of fluorinated carbon KAU (obtained by fruit stones carbonization and activation, S.sub.BET=1100 m.sup.2/g) modified with Arcton 3 (Freon R-13,CF.sub.3Cl) at 550 C., that contain 1.06 mmol/g of fluorine and 0.88 mmol/g of chlorine, BET surface 752 m.sup.2/g, was treated in a stream of mixture argon and hydrogen sulfide (50 ml/min of argon, 2 ml/min of hydrogen sulfide) at 450 C. for 3 h. Subsequently, the resulting product was cooled in the reaction gas mixture and treated oxidation mixture and further as described in Example 1. The resulting fluorine-containing contains 1.81 mmol/ g of fluorine, 0.85 mmol/g of chlorine and 0.25 mmol/g of sulfur and has BET surface 680 m.sup.2/g (FIG. 7). The results TPD-mass studies sulfur desorption occurs in close to the product of Example 1 temperature range, as well as SO.sub.2. [0028] 4. 1 g of multilayer carbon nanotubes (BET specific surface area of 180 m.sup.2/g), which was treated with R-134a, Forane (H.sub.2FC-CF.sub.3) at 550 C., which contains fluorine in an amount of 0.25 mmol/g, were treated 5 ml 25% of oleum (25% SO.sub.3 solution in H.sub.2SO.sub.4) at 60 C. After the reaction precipitate was filtered, washed with concentrated sulfuric acid, water, soda solution, 5% hydrochloric acid and again with water to neutral pH. The content of fluorine and sulfur in the product was 0.22 and 0.08 mmol/g, respectively. [0029] 5. 1 g of activated carbon fibers (raw material cellulose, BET surface area above 800 m.sup.2/g) which was treated with the refrigerant R-125, pentafluoroethane, at a temperature of 600 C., fluorine content which is 1.45 mmol/g, was treated with 2 g of chlorosulfonic acid, HSO.sub.3Cl, at 60 C. for 3 hours, then treated with a product similar to Example 4. The resulting sulfurized product contains 1.30 mmol/g of fluoride, 0.27 mmol/g of sulfur and 0.03 mmol/g of chlorine. [0030] 6. 1 g of carbon black K-354 that was processed with 2,2,2-trifluoroethanol (CF.sub.3CH.sub.2OH, 99+%, Alfa Aesar) at a temperature of 660 C. (fluorine content is 1.05 mmol/g) was mixed with 5 g of thiourea and placed in a Pyrex vial with thin exit. Ampoule was carefully heated to a temperature of 250 C. Moreover, there was a decomposition of sulfur-containing reagent to form gaseous products: CS.sub.2, H.sub.2NCN, ammonia and HNCS. After the evolution of gaseous products from reaction medium temperature was increased to 350 C. and vial evacuated was evacuated. After, the residue was washed with isopropanol, water, and oxidized similar to Example 1. The resulting sulfurized material contains 0.98 mmol/g of fluorine and 0.12 mmol/g of sulfur. According to TPD-mass research, evolving of sulfur dioxide observed in a temperature range of 130-450 C. [0031] 7. 3 g sample of fluorinated carbon material obtained by reacting of activated carbon Norit 830W with R-134a at 600 C. (fluorine content is 1.93 mmol/g) in Teflon vial was mixed with a mixture of sodium polysulfides hydrates and autoclaved at 175 C. for 12 hours. The resulting product was subjected to oxidation with 20% hydrogen peroxide in 50% acetic acid for 18 hours and further processed as described in Example 1. The resulting sulfurized product contains 1.85 mmol/g of fluoride and 0.44 mmol/g of sulfur. According to TPD-mass, only one product of sulfur desorption, SO.sub.2, was observed. [0032] 8. A sample of 1.25 g of BAU-A activated carbon (raw material is the birch wood), that was treated with tetrafluoroethane, R-134a, Forane (H.sub.2FC-CF.sub.3), at 500 C., which contains 0.42 mmol/g of fluorine and has a BET surface area about 550 m.sup.2/g was put in contact with argon, saturated with a steam of bis-tert-butyl disulfide (Di-tent-butyl disulfide, (CH.sub.3).sub.3CSSC(CH.sub.3).sub.3, Sigma-Aldrich, 97%). Reactant gas mixture was obtained by bubbling of argon through a bis-tert-butyl disulfide at room temperature. Steam treatment was continued for 40 minutes at 475 C., and then passed through a sample of pure argon for 40 minutes and then the resulting sample was oxidized and processed similar to Example 1. The resulting sulfurized material contains 0.35 mmol/g of fluorine and 0.85 mmol/g of sulfur. [0033] 9. 1 g sample of fluorinated carbon material obtained by reacting of activated carbon Norit 830W with R-125 at 600 C. (fluorine content is 2.30 mmol/g) was impregnated with 2.5 ml of a saturated solution of elemental sulfur in benzene, dried at 120 C. and placed in a glass vial. Vial was evacuated, sealed and heated to 465 C. for 2 hours. The resulting product is treated with 20% hydrogen peroxide acetic acid solution for 24 hours and then washed similar to Example 1. The resulting material contains 1.92 mmol/g of fluorine and 0.97 mmol/g of sulfur. According TG-DTG / TPD-IR data (Ar, 50 ml/min flow rate, 10 K./min heating rate, 60 mg sample, 100 mm long IR-cuvette with NaCl windows), the sample desorb sulfur in SO.sub.2 form at mediate high temperature range (FIG. 8). For comparison, industrial sulfocoal CK-1 that was washed by sodium carbonate to remove physisorbed H.sub.2SO.sub.4, after HCl 5% solution, to renew H-form of sulfonic groups, and by water again, to pH 4.5, was tested by similarly method. It was shown, that SO.sub.2 desorbs from sample in the temperature of the range 290-590 C. (260-450 C. for CK-1) and contain significantly less (in comparison with sulfonated coal CK-1, CAS# 69013-20-3) of high temperature oxygen surface complexes, that desorbs in the temperature of the range 450-700 C. SO.sub.2 evolving in this temperature range is agreed with TPD-IR data.
[0034] Evidently, numerous variations and modifications of the present invention are possible in light of the above studies. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described in present Examples.
CITATIONS
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